Weight is the force acting on an object due to gravitational attraction .

How does the mass of a planet affect its gravitational field strength ?

The greater the mass of the planet, the greater its gravitational field strength, giving a larger attractive force towards its centre.

Why is it easier to lift a mass on the surface of the Moon than on the Earth ?

The Moon's gravitational field strength is less than the Earth's, so objects have less weight there.

True or False? An object's mass changes when it travels from Earth to Jupiter, but its weight stays the same.

False. The object's mass stays the same everywhere in space, but its weight increases on Jupiter because Jupiter's gravitational field strength is greater.

Name three types of object found in the Solar System, other than the Sun and the eight planets.

Natural satellites , artificial satellites , dwarf planets , asteroids and comets .

Why does a dwarf planet not pull in nearby objects, unlike a full planet?

A dwarf planet's gravitational field is not strong enough to have pulled in nearby objects.

An asteroid is a small rocky object that orbits the Sun, mostly found in the asteroid belt between Mars and Jupiter .

State the 8 planets of the Solar System in order of increasing distance from the Sun.

Mercury , Venus , Earth , Mars , Jupiter , Saturn , Uranus , Neptune .

Mercury, Venus, Earth and Mars are the ______ planets, while Jupiter, Saturn, Uranus and Neptune are the ______ planets.

Mercury, Venus, Earth and Mars are the rocky planets, while Jupiter, Saturn, Uranus and Neptune are the gas planets.

What was the geocentric model of the Solar System, and who first proposed replacing it?

The geocentric model placed the Earth at the centre of the Solar System. Nicolas Copernicus first suggested a heliocentric model with the Sun at the centre.

True or False? The invention of the telescope provided evidence that supported the geocentric model.

False. Telescope observations, such as the moons of Jupiter orbiting Jupiter and not the Earth, provided evidence against the geocentric model.

What provides the force that keeps a smaller body in orbit around a larger body?

Gravity , which acts towards the centre of the larger body.

Why is an object moving in a circular orbit at constant speed still accelerating ?

Its direction is constantly changing, so its velocity is constantly changing, and acceleration is the rate of change of velocity.

In which direction must the resultant force act to keep an object in a circular orbit ?

At right angles to the object's instantaneous velocity , always towards the centre of the orbit.

Name two ways in which the orbits of different planets around the Sun differ.

They orbit at different distances from the Sun, at different speeds , and take different amounts of time to orbit the Sun.

The closer a moon is to its planet, the ______ its orbital time and the ______ its orbital speed.

The closer a moon is to its planet, the shorter its orbital time and the greater its orbital speed.

True or False? If an artificial satellite travels too fast for its orbital radius, it will spiral inwards towards the object it is orbiting.

False. If the satellite is too fast, gravitational attraction cannot provide enough force to keep it in orbit, so its radius increases and it spirals into space .

What shape are the orbits of most comets ?

Elliptical (stretched circles), though still stable.

What happens to a comet's orbital radius and speed as it approaches the Sun?

The radius decreases and the orbital speed increases due to the Sun's stronger gravitational pull.

What happens to a comet's orbital radius and speed as it travels further from the Sun?

The radius increases and the orbital speed decreases due to a weaker gravitational pull.

What energy transfer occurs as a comet approaches the Sun?

The comet loses gravitational potential energy and gains kinetic energy.

For a stable orbit, the ______ of an orbit must change if the object's orbital ______ changes.

For a stable orbit, the radius of an orbit must change if the object's orbital speed changes.

True or False? A comet's tail always points towards the Sun.

False. As the comet's icy body sublimates near the Sun, it forms a tail that always points away from the Sun.

What are the two forces that balance to hold a star in equilibrium ?

The inward force of gravity and the outward force from the pressure of thermal expansion of hot gases.

Define equilibrium in the context of a star.

Equilibrium is when the inward pull of gravity and the outward force from thermal expansion acting on a star are equal .

What happens to a star if its temperature increases ?

The outward pressure increases, causing the star to expand .

What happens to a star if its temperature drops ?

The outward pressure decreases, causing the star to contract .

A star's forces become unbalanced when ______ in its core ceases at the end of its life, causing the star to expand or contract.

A star's forces become unbalanced when fusion in its core ceases at the end of its life, causing the star to expand or contract.

True or False? Main sequence stars remain stable for millions of years because the inward and outward forces acting on them are equal.

True. When gravity and the outward pressure force are balanced, the star is in equilibrium and remains stable.

A nebula is a giant cloud of hydrogen gas and dust from which all stars form.

What happens to the density and temperature of a protostar as gravity pulls its particles closer together?

The density increases , causing more frequent particle collisions, which increases the temperature .

What condition must be met for a protostar to become a main sequence star ?

It must become hot enough for fusion reactions to begin in its core, so that thermal expansion balances the force of gravity.

Why does a red giant's core shrink at the end of the main sequence stage?

The star runs out of fuel, so the outward pressure force dies down and the inward force due to gravity becomes greater , causing the core to shrink and heat up.

A solar mass star ends its life by ejecting its outer layers as a ______ , leaving behind a core that collapses into a ______ .

A solar mass star ends its life by ejecting its outer layers as a planetary nebula , leaving behind a core that collapses into a white dwarf .

True or False? A white dwarf's energy output increases over time as it cools.

False. As a white dwarf cools, the amount of energy it emits decreases .

State the order of stages in the life cycle of a solar mass star.

Nebula → protostar → main sequence star → red giant → planetary nebula → white dwarf .

How does a protostar form from a nebula, and why does its temperature increase?

Gravity pulls the particles in the nebula closer together, forming a hot ball of gas. As the particles get closer, density increases , causing more frequent collisions, which increases the temperature .

Why does the core of a main sequence star shrink and heat up as it runs out of fuel?

The inward force due to gravity becomes greater than the outward force due to the pressure of the expanding gases, so the core shrinks and heats up.

Once the reactions inside the red supergiant finish, the core collapses suddenly and rebounds, causing a gigantic explosion called a ______ .

Once the reactions inside the red supergiant finish, the core collapses suddenly and rebounds, causing a gigantic explosion called a supernova .

True or False? A neutron star always collapses further to form a black hole.

False. Only in the case of the largest stars does the neutron star continue to collapse under gravity until it forms a black hole .

State the correct order of stages in the life cycle of a star much larger than the Sun, from nebula onwards.

Nebula → protostar → main sequence star → red supergiant → supernova → neutron star (or black hole ).

GCSEPhysicsEdexcelFlashcards7. AstronomyThe Solar System & Lifecycles of Stars

The Solar System & Lifecycles of Stars (Edexcel GCSE Physics): Flashcards

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FrontGravity & Weight
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Cards in this collection (43)

Define weight.
Weight is the force acting on an object due to gravitational attraction.
What is the approximate gravitational field strength on the surface of the Earth?
Approximately 10 N/kg.
How does the mass of a planet affect its gravitational field strength?
The greater the mass of the planet, the greater its gravitational field strength, giving a larger attractive force towards its centre.
Why is it easier to lift a mass on the surface of the Moon than on the Earth?
The Moon's gravitational field strength is less than the Earth's, so objects have less weight there.
True or False?
An object's mass changes when it travels from Earth to Jupiter, but its weight stays the same.
False.
The object's mass stays the same everywhere in space, but its weight increases on Jupiter because Jupiter's gravitational field strength is greater.
Name three types of object found in the Solar System, other than the Sun and the eight planets.
Natural satellites, artificial satellites, dwarf planets, asteroids and comets.
Why does a dwarf planet not pull in nearby objects, unlike a full planet?
A dwarf planet's gravitational field is not strong enough to have pulled in nearby objects.
Define asteroid.
An asteroid is a small rocky object that orbits the Sun, mostly found in the asteroid belt between Mars and Jupiter.
State the 8 planets of the Solar System in order of increasing distance from the Sun.
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
Mercury, Venus, Earth and Mars are the ______ planets, while Jupiter, Saturn, Uranus and Neptune are the ______ planets.
Mercury, Venus, Earth and Mars are the rocky planets, while Jupiter, Saturn, Uranus and Neptune are the gas planets.
Light travels at 3 × 10⁸ m/s and takes 8 minutes to reach the Earth from the Sun. What is the distance of the Earth from the Sun?
The distance of the Earth from the Sun is $1.4 \times 10^{11} m$ .
- $distance = speed \times time$
- $distance = (3 \times 10^{8}) \times (8 \times 60)$
- $distance = 1.4 \times 10^{11} m$
What was the geocentric model of the Solar System, and who first proposed replacing it?
The geocentric model placed the Earth at the centre of the Solar System. Nicolas Copernicus first suggested a heliocentric model with the Sun at the centre.
True or False?
The invention of the telescope provided evidence that supported the geocentric model.
False.
Telescope observations, such as the moons of Jupiter orbiting Jupiter and not the Earth, provided evidence against the geocentric model.
What provides the force that keeps a smaller body in orbit around a larger body?
Gravity, which acts towards the centre of the larger body.
Why is an object moving in a circular orbit at constant speed still accelerating?
Its direction is constantly changing, so its velocity is constantly changing, and acceleration is the rate of change of velocity.
In which direction must the resultant force act to keep an object in a circular orbit?
At right angles to the object's instantaneous velocity, always towards the centre of the orbit.
Name two ways in which the orbits of different planets around the Sun differ.
They orbit at different distances from the Sun, at different speeds, and take different amounts of time to orbit the Sun.
The closer a moon is to its planet, the ______ its orbital time and the ______ its orbital speed.
The closer a moon is to its planet, the shorter its orbital time and the greater its orbital speed.
True or False?
If an artificial satellite travels too fast for its orbital radius, it will spiral inwards towards the object it is orbiting.
False.
If the satellite is too fast, gravitational attraction cannot provide enough force to keep it in orbit, so its radius increases and it spirals into space.
What shape are the orbits of most comets?
Elliptical (stretched circles), though still stable.
What happens to a comet's orbital radius and speed as it approaches the Sun?
The radius decreases and the orbital speed increases due to the Sun's stronger gravitational pull.
What happens to a comet's orbital radius and speed as it travels further from the Sun?
The radius increases and the orbital speed decreases due to a weaker gravitational pull.
What energy transfer occurs as a comet approaches the Sun?
The comet loses gravitational potential energy and gains kinetic energy.
For a stable orbit, the ______ of an orbit must change if the object's orbital ______ changes.
For a stable orbit, the radius of an orbit must change if the object's orbital speed changes.
True or False?
A comet's tail always points towards the Sun.
False.
As the comet's icy body sublimates near the Sun, it forms a tail that always points away from the Sun.
What are the two forces that balance to hold a star in equilibrium?
The inward force of gravity and the outward force from the pressure of thermal expansion of hot gases.
Define equilibrium in the context of a star.
Equilibrium is when the inward pull of gravity and the outward force from thermal expansion acting on a star are equal.
What happens to a star if its temperature increases?
The outward pressure increases, causing the star to expand.
What happens to a star if its temperature drops?
The outward pressure decreases, causing the star to contract.
A star's forces become unbalanced when ______ in its core ceases at the end of its life, causing the star to expand or contract.
A star's forces become unbalanced when fusion in its core ceases at the end of its life, causing the star to expand or contract.
True or False?
Main sequence stars remain stable for millions of years because the inward and outward forces acting on them are equal.
True.
When gravity and the outward pressure force are balanced, the star is in equilibrium and remains stable.
Define nebula.
A nebula is a giant cloud of hydrogen gas and dust from which all stars form.
What happens to the density and temperature of a protostar as gravity pulls its particles closer together?
The density increases, causing more frequent particle collisions, which increases the temperature.
What condition must be met for a protostar to become a main sequence star?
It must become hot enough for fusion reactions to begin in its core, so that thermal expansion balances the force of gravity.
Why does a red giant's core shrink at the end of the main sequence stage?
The star runs out of fuel, so the outward pressure force dies down and the inward force due to gravity becomes greater, causing the core to shrink and heat up.
A solar mass star ends its life by ejecting its outer layers as a ______, leaving behind a core that collapses into a ______.
A solar mass star ends its life by ejecting its outer layers as a planetary nebula, leaving behind a core that collapses into a white dwarf.
True or False?
A white dwarf's energy output increases over time as it cools.
False.
As a white dwarf cools, the amount of energy it emits decreases.
State the order of stages in the life cycle of a solar mass star.
Nebula → protostar → main sequence star → red giant → planetary nebula → white dwarf.
How does a protostar form from a nebula, and why does its temperature increase?
Gravity pulls the particles in the nebula closer together, forming a hot ball of gas. As the particles get closer, density increases, causing more frequent collisions, which increases the temperature.
Why does the core of a main sequence star shrink and heat up as it runs out of fuel?
The inward force due to gravity becomes greater than the outward force due to the pressure of the expanding gases, so the core shrinks and heats up.
Once the reactions inside the red supergiant finish, the core collapses suddenly and rebounds, causing a gigantic explosion called a ______.
Once the reactions inside the red supergiant finish, the core collapses suddenly and rebounds, causing a gigantic explosion called a supernova.
True or False?
A neutron star always collapses further to form a black hole.
False.
Only in the case of the largest stars does the neutron star continue to collapse under gravity until it forms a black hole.
State the correct order of stages in the life cycle of a star much larger than the Sun, from nebula onwards.
Nebula → protostar → main sequence star → red supergiant → supernova → neutron star (or black hole).

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